Coating apparatus



Jan. 7, 1941-v H. E. VAN DERHol-:F

comme APPARATUS Filed April l5, 1959 Patented Jan. 7, 1941 PATENT" I oFFlcE 2,221,988 ooATrNG APPARATUS Henry E. Van Derhoef, Rochester, N. Y., assignor 'to Eastman Kodak Company, Rochester, N. Y.,

a corporation ot New Jersey Application April I3, 1939, Serial No. 267,640

4 Claims. (CL 91-51) This invention relates to coating apparatus and more particularly to coating apparatus for continuously coating sheets or films with various coating solutions.

In such coating apparatus it is customary to rotate an applicator roll partially submerged in a hopper containing the coating solution, and the sheet or lm to be coated is passed between a guiding roll and the applicator roll so that the sheet or lm becomes coated on one side with the coating solution. The coated sheet or film is then conducted through other suitable processes as may be desired.

It has been experienced in employing such apparatus that the maintenance of a constant flow of solution to andjrom the hopper determines to a great extent whether or not the applied coating will be uniform over the expanse of the surface being coated.

'Ihe problem of maintaining a constant supply .of coating solution in the coating hopper, as Well as the even distribution of the coating solution throughout the hopper has been given considerable study. Various schemes for introducing and removing the coating solution have been devised. 'Ihese vary from the so-called flow type hopper tq that known as the center feed type hopper. While these devices operate to produce satisfactory coatings, they require more regulation and adjustment for their proper operation than is desirable. With the flow type hopper it is rather dilcult'to provide a constant Y supply of coating solution to the flow hopper, and with the center feed hopper it is difficult to determine the right proportions of openings for a definite distribution of the supply throughout the length of the hopper.

Some difficulty has also been experienced in keeping the composition of the bath within proper limits and to removev foreign matter, which may from time to time enter the bath from various sources, while the coating apparatus is in operation.

An object of the present invention is, therefore, van improved coating apparatus in which the coating solution is uniformly distributed to the coating hopper and to the-applicator roll at the regular rate.

Another object of the invention is an improved coating apparatus in which the coating solution may be uniformly removed from the coating hopper in proportion to the rate at which it is introduced into the hopper.

In accordance with one feature of the invention these and other objects are attained by employing a coating apparatus in which the coating solution is introduced into the coating hopper by a fluted or toothed roller which extends parallel to the applicator roll and rotates at regular intervals in a supply hopper containing a 5 supply of the coating solution. The rotation of the toothed roller transfers, by means of its teeth and grooves therebetween, uniform amounts of solution all along the length of the 4coating hopper at a position parallel to and equidistant from l the applicator roll. Preferably the toothed roller is substantially the same length as the applicator roll.

In accordance with another feature of the invention a similar fluted or toothed roller may be l positioned also adjacent and parallel to the applicator roll on the opposite side from the first roller, in an outflow hopper and may be caused to rotate at regular intervals to remove the coating solution from the\coating hopper.

The present invention istparticularly adapted for use in the manufacture of photographic film.

In his art; a film base or support is first formed and this support is thenk coated with a suitable subbng layer prior to the application of a light sensitive emulsion.

Certain of the undesirable coating methods heretofore employed for this purpose produce longitudinal lines running along the `length of the support to which the subbng solution is be- 3U ing applied. These may be caused by non-uniform mixing of the fresh subbng solution with the solution already in the coating hopper as Well as caused by uneven ow lines on the surface of the solution. Also in certain coating apparatus of the prior art there are dead" areas in which particles of the film base may collect and where the solution may be of a different concentration or composition than at other porl tions of the hopper. Such undesirable factors 0 cause irregularities and imperfecions in the resulting photographic film.

My methed of introducing and removing the coating solution by toothed rolls eliminates such undesirable features and results in uniform coatings on film base or othersuch supports.

The invention will be more clearly understood by reference to the following detaileddescription and drawing in which:

Fig. 1 is an end elevation view in section of my 50 improved coating apparatus;

Fig. 2 is an elevation view of a side section taken on line 2-2 of Fig. 1;

Fig. 3 is an enlarged end sectional View taken on line 3-3 Fig. 2 showing the toothed roller u Din 3l).

and supply hopper positioned adjacent the applicator roll; and 1 Fig. 4 is a view in section showing the toothed roller and outflow hopper for removing the solution from the coating hopper.'

Referring to Figs. 1 and 2 there is shown a coating apparatus comprisingl a base 5, a coating hopper 6, an applicator roll 1 and a guide roll 8 around which a portion of a continuous strip of material to be coated is shown at 9. The guide roll 8 may be suitably mounted and rotated by apparatus not shown.

The supply hopper is shown at I I having a concave portion I2 extending longitudinally thereof. In the concave portion I2 of the supply hoppe/r I I, is mounted in rotatable counterclockwise arrangement, a toothed feed roller I3. This tootiuad feed roller I3, as shown more clearly in Fig. 3 rests on the concave portion I2 of hopper I I and is rotated around its pintles one of which is shown at I5 engaging slotted block I by means of slot I4. Block II) is removably attached to the wall I6, and when it is desired to remove roller I3 from the supply hopper I2 for the purpose of cleaning and so forth block I0 is rst removed permitting free access to the roller. A similar slotted block is positioned atthepposite end of the toothed roller I3.

The toothed roller I3 is turned by the driving mechanism mounted in chamber I1, this chamber being formed by side walls I8' and I9, base 2|, top 23 and front and back Walls 3l and 32. The driving mechanism'comprises a pawl 22 which engages the toothed roller I3 and turns the roller in accordance with the rotation of shaft 24 which motion is transmitted to the pawl 22 through worm 25, worm gear 26, an adjustable pin 30, pivoted lever 21 and stud 28. As shown in Fig. 1 the driving shaft 24 is mounted in suitable bearings-in the walls I 8 and I9 and, as shown in Fig. 2, the pivoted lever 21 is pivoted on bolt 33 which engages wall 32 and the worm gear 26 is rotatably mounted on shaft 34.

As shown in Figs. 1 and 2 the operation of lever 21 depends on the movement of the adjustable This pin 30 as shown in Fig. 2 is associated with a slotted member 35 through its attachment witliqashoe 36 which is adapted to slide in the slot 31. As Worrmgear 26 rotates, the pin 30 will follow a circular orbit concentric with shaft 34, the diameter of such orbit being variable according to the position in slot 31 in which the shoe 36 is changed by the pin 30. I'he pin 30 thus will move up and down in slot 20 of lever 21 imparting a rocking movement to the latter, and this movement will cause pawl 22 first to engage the toothed roller I3 and rotate it in a counterclockwise direction a fraction of one revolution and then to slip back over the roller and into engaging position. The degree of such fractional rotation may be varied by loosening the clamped shoe 36 and relocating it in a different position in the slot 31.` 1

As will be apparent from Fig. 1 the mechanism for removing coating solution from the coating hopper 6 is quite similar to that above described for introducing the coating solution into the coating hoppen-,

As in the case of the toothed feed roller I3, the

toothed roller 4I is rotatably mounted in the' outflow hopper 42 which has a concave portion 43 extending longitudinally thereof. The radius of curvature of the concave section 43 of the hopper 42 and that of the toothed roller 4I are substantially equal and, as shown in Figs. 1 and 4, the

toothed roller 4I rests upon the outow hopper so that substantially no solution can pass from the coating hopper 6 to outflow hopper 42 without the rotation of the toothed roller 4 I. 'Ihe toothed roller 4I, as shown in Fig. 4, is'rotatably maintained in the outflow hopper 43 by means of slotted block I0 having a slot I4 therein.

The toothed roller 4I is turned by a driving mechanism similar to that described for rolle'r I3, mounted in chamber 44. This chamber is formed by side walls 54 and 45, the end walls 3| and 32. and top wall 23, a portion of which is shown in Fig. 2. 'Ihe driving mechanism comprises a pawl 46 which engages the toothed roller 4I and turns the roller in accordance with the rotation of shaft 41 which motion is transmitted to the pawl 46 through worm 48, worm gear 49, adjustable shoe 50, pin I, pivoted lever 52 and stud 53. This mechanism operates the same as that for rotating the toothed feed roller I3 and is mounted in a similar manner. It is obvious from the drawing that pawl 46 turns toothed roller 4I by a thrust action while pawl 22 turns toothed roller I3 by a pulling action. It will also be apparent thatthe teeth of both the toothed rollers I3 and 4I are so shaped that they will provide drainage surfaces when the teeth lift out of the solution thus avoiding the return of the coating solution to either the supply hopper or the coating hopper.

Any suitable motive force for operating the mechanism can be "connected to shafts 24 and 41 as will be understood. If desired the temperature of the coating solution may be regulated before it is introduced into the hopper, and the hopper 6 may be suitably heated if desired.

To operate the apparatus coating, solution is permitted to flow through inlet 55 to fillthe supply hopper I I. The hopper 6 may be filled from a direct supply pipe, not shown, to a level as is indicated in Figs. 3 and 4. The strip or film base 9 to be coated is suitably positioned around guide roll 8, and roll 8 is adjusted by means not shown to permit the film base 9 to contact the periphery of applicator roll 1 which is suitably mounted an rotated by means, not shown, in hopper 6.

The apparatus is now ready for operation and toothed rollers I3 and 4I \and the applicator roll 1 and guide roll 8 are "cased to rotate. As is indicated in Fig. 1, the toothed roller I3 turns in a counterclockwise direction While the adjacent applicator roll 1 turns in a clockwise direction. It will be evident that this will permit a surface layer of fresh coating solution to continually come inscontact with the applicator roll 1 and be carried up into contact with the film base 9.

As previously explained the solution owing to its uniform distribution to the hopper 6, contacts the applicator roll 1 along its whole length very `evenly and this eliminates longitudinal stripes in the coated surface. Furthermore this arrangement assures that the solution contacting the film base will be of substantially uniform composition and eliminates dead areas in the coating bath.

As will be evident from reference to Figs. 1 and 4 toothed roller 4I turns in counterclockwise direction and this will uniformly remove coating solution from hopper 6 and permit it to flow through drain 56. If foreign matter such as flakes from the film base, or the like, fall into the hopper they will be removed from the. surface of the liquid without being mixed into the remainder 0f the coating solution. Also the portion of the coating solution which may be carried over by the applicator roll will normally be carried out through the outflow hopper 42 and drain 56 without the possibility of contaminating the remainder ofthe solution in the coating hopper.

It will be understood that the rates of rotation of the applicator and guide rolls and the input and output toothed rolls may be varied as is desired. This will depend somewhat on the viscosity of the solution and characteristics of the lm.

This apparatus permits the production of a very uniformly coated sheet or film and overcomes many undesirable features of apparatus now commonly employed.

What I claim is:

1. In an apparatus for coating films or sheets, a coating hopper adapted to contain a coating solution, an applicator roll positioned to be partially submerged in the solution and adapted to coat the solution onto a film, a feed hopper adapted to contain a supply of coating solution positioned adjacent said coating hopper, and a uted roller having flutes substantially parallel to the length of the roll rotatably mounted between said hoppers and in contact with said feed hopper solution and adapted to convey solution by means of the flutes from the feed hopper to the coating hopper when rotated in a counterclockwise direction.

2. In an apparatus for coating films or sheets, a coating hopper adapted to contain coating solution, an applicator roll positioned to be partially submerged in the solution adapted to coat the solution onto a film, a feed hopper adapted to contain a supply of coating solution positioned adjacent said coating hopper, and a uted roller having flutes substantially parallel to the length of the roller rotatably mounted between said hoppers, and in contact with said solution and parallel to the applicator roll, adapted to convey solution by means of the flutes from the feed hopper to the coating hopper when rotated in a counterclockwise direction.

3. In apparatus for coating films or sheets, a

f coating hopper adapted to contain a coating solution, means for maintaining the supply of solution substantially constant, an applicator roll positioned to be partially submerged in the solution adapted to coat the solution onto a lm, an output hopper adapted to conduct solution away from said coating hopper, and a fluted roller having flutes substantially parallel to the length of the roll rotatably mounted between said coating hopper and output hopper and in contact with the solution in the coating hopper and mounted parallel with the applicator roll adapted to transfer solution by means of the flutes from the coating hopper to the output hopper when rotated in a counterclockwise direction.

4. In apparatus for coating lms or sheets, a coating hopper adapted to contain a coating solution, an applicator roll positioned to be partially submerged in the solution adapted to coat the solution onto a film, a feed hopper adapted to contain a supply of coating solution positioned at one side of said coating hopper, a fluted roller having flutes substantially parallel to the length of the roll rotatably mounted between said hoppers parallel to the applicator roll and of substantially the same length and normally in contact with the solution in the feed hopper adapted to transfer the solution from the feed hopper to the coating hopper by/neans of its flutes when rotated, an output lopper positioned at the opposite side of the coating hopper adapted to conduct solution away from said coating hopper, and a iluted roller having flutes substantially parallel to the length of the roll rotatably mounted between said coating hopper and output hopper and normally in contact with the solution in the coating hopper and parallel to the applicator roll adapted to transfer solution from the coating hopper to the output hopper by means of its flutes when rotated, and means for rotating said uted rollers in counterclockwise direction said first mentioned roller adapted to be rotated at a rate sufficient to maintain said solution in said coating hopper at a predetermined level.

HENRY E. VAN DERHOEF. 

